Air conditioning duct and method for mounting same

ABSTRACT

An air conditioning duct to be positioned on a rear surface of a vehicular instrument panel ( 10 ). The duct ( 20 ) allows an air conditioning duct with complicated share to be formed of a plurality of separate cylindrical members ( 30  to  60 ). Joining the plurality of cylindrical members with a plurality of fixture members ( 71 ) allows the air conditioning duct to be obtained. The cylindrical members have leg portions ( 39 A to  39 C,  45, 55, 65 ) designed to be mounted to the instrument panel.

TECHNICAL FIELD

[0001] The present invention relates to an air conditioning duct to bepositioned at a rear wall side of a vehicular instrument panel and amethod for mounting the same.

BACKGROUND ART

[0002] In general vehicles including motor vehicles, there are manyinstances where the vehicles are mounted with air conditioning unitswith a view to provide a comfortable surrounding for passengers. Avehicular air conditioning system includes an air conditioning ductpositioned at a rear side of an instrument panel mounted in a front partof a passenger compartment to allow cold air or hot air to be blown outinto the passenger compartment through the duct. Such a duct isdisclosed in, for example, Japanese Patent Laid-Open Publication No.HEI-11-321287.

[0003] The duct disclosed in Japanese Patent Laid-Open Publication No.HEI-11-321287 comprises a plurality of duct sections, interconnectingsegments for interconnecting these duct sections and a leg portionprotruding from one of the ducts, with the leg portion and the one ofthe duct sections being unitarily formed by a blow forming technology toform the air conditioning duct. Securing the aforementioned leg portionto the rear surface of the instrument panel 1 by a vibrating depositionallows the aforementioned air conditioning duct to be mounted to theinstrument panel.

[0004] In order to improve the comfortable surrounding in the passengercompartment, it is desired for air conditioning to be efficientlycarried out to preclude an uneven temperature distribution in thepassenger compartment. To meet such a demand, it is a point that aplurality of air blowout openings must be located at respective suitablepositions and the volumes of air discharged from the respective airblowout openings must be suitably distributed. In order to optimize thevolumes of air to be distributed, it is thought that the airconditioning duct is formed with a plurality of partitions or with aplurality of air inlets. With such a structure, the air conditioningduct inevitably results in a complicated shape. When forming the airconditioning duct with such a complicated structure with the use of theabovementioned conventional technology, there is a limit in addressingissues of troublesome processing steps and complicated forming dies.

DISCLOSURE OF THE INVENTION

[0005] It is therefore an object of the present invention to provide atechnology for enabling an air conditioning duct with a complicatedstructure, which is mounted to a vehicular instrument panel, to bemanufactured in an easy manner.

[0006] According to a first aspect of the present invention, there isprovided an air conditioning duct adapted to be located at a rearsurface of a vehicular instrument panel, which comprises a firstcylindrical body; a second cylindrical body placed along the firstcylindrical body; a plurality of fixture members for joining the firstand second cylindrical bodies to one another; and a leg portionextending from at least one of the first and second cylindrical bodiestoward the vehicular instrument panel.

[0007] Thus, the present invention allows one piece of the airconditioning duct with a complicated structure to be manufactured withseparate pieces of the cylindrical bodies. Joining these plural piecesof the cylindrical bodies with the plurality of the fixture membersenables production of a single piece of the air conditioning duct. Theunitarily formed air conditioning duct is mounted to the vehicularinstrument panel via the leg portion extending toward the same. Thus,even when the air conditioning duct has the complicated structure, thepresence of the plurality of the separate cylindrical bodies allows theindividual cylindrical bodies to be formed in relatively simplifiedstructures. This results in an easy production of the air conditioningduct.

[0008] Preferably, the fixture members are placed along the longitudinaldirection of the first cylindrical body. Joining the first and secondcylindrical bodies with the plurality of the fixture members allows theair conditioning duct to have an adequate entire shape and rigidity toprovide a preferable result.

[0009] In a preferred form, at least one of the fixture members islocated in the vicinity of the openings of the first and secondcylindrical bodies. That is, the fixture member remains in the vicinityof the openings within worker's reach, with a resultant improvement overthe joining workability.

[0010] Desirably, the first and second cylindrical bodies include airblowout tubes, respectively, which extend toward the aforementionedvehicular instrument panel. Outlets of the air blowout tubes are formedin bell-mouthed shapes so as to mate with the air discharge pipesmounted at the aforementioned vehicular instrument panel. Thus, evenwhen the outlets of the air blowout tubes are slightly dislocated withrespect to the air bleed openings of the instrument panel, mating theoutlets of the air blowout tubes with the air discharge pipes enables amatching of the outlets of the air blowout tubes with respect to the airdischarge pipes in an easy manner.

[0011] The leg portion may be designed to be mounted to the vehicularinstrument panel by the vibrating deposition and has a mount surfaceformed with a plurality of projections. Thus, the presence of theplurality of the projections allows a contact surface area per eachprojection to have a lower value than that of a single piece ofprojection as proposed in prior art practice. The presence of theindividual projections with reduced contact surface areas decreases theheat value, which occurs during the vibrating deposition, by an amountequal to the reduced contact surface area. It is possible to furtherpreclude a sink mark or irregular gloss caused on an external surface ofthe instrument panel due to heat generated during the vibratingdeposition.

[0012] According to a second aspect of the present invention, there isprovided a method for mounting an air conditioning duct, comprising thesteps of: preparing a first cylindrical body and a second cylindricalbody which are unitarily formed with leg portions, respectively; placingthe first cylindrical body and the second cylindrical body along to oneanother and joining the first and second cylindrical bodies with aplurality of fixture members; and mounting the respective leg portionsto the vehicular instrument panel by a vibrating deposition.

[0013] Thus, in accordance with the assembling method of the presentinvention, the second cylindrical body is placed along the firstcylindrical body and both of these components are joined to one anotherwith the plural pieces of the fixture members and, subsequently, the legportion is mounted to the instrument panel by the vibrating deposition,resulting in an ease of fabrication of the air conditioning duct evenwith a complicated structure. In addition, since the unitarily formedair conditioning duct is mounted to the instrument panel with a workmerely having the vibrating deposition, workability for mounting the airconditioning duct is highly improved.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Certain preferred embodiments of the present invention will bedescribed in detail below, by way of example only, with reference to theaccompanying drawings, in which:

[0015]FIG. 1 is a front view illustrating a vehicular instrument panel;

[0016]FIG. 2 is a front view of an air conditioning duct according tothe present invention;

[0017]FIG. 3 is an exploded view of the air conditioning duct shown inFIG. 2;

[0018]FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. 1;

[0019]FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 1,illustrating a state in which a left horizontal section of a cylindricaldefroster member is coupled to a left horizontal section of a leftcylindrical ventilating member;

[0020]FIG. 6 is a detailed view of a section 6 of FIG. 5, illustrating astate in which a blowout opening of the left horizontal section of thecylindrical defroster member is coupled to a defroster blowout opening;

[0021]FIG. 7 is a detailed view of a section 7 of FIG. 5, illustrating astate in which the leg portion of the left cylindrical ventilatingmember is mounted to a rear surface of the instrument panel;

[0022]FIG. 8 is a cross-sectional view taken along line 8-8 of FIG. 1,illustrating a state in which a left suspended section of the leftcylindrical ventilating member is coupled to a left suspended section ofthe cylindrical defroster member;

[0023]FIGS. 9A and 9B are views illustrating a relationship between anair blowout tube and an air discharge pipe;

[0024]FIGS. 10A to 10D are views illustrating a sequence of manufactureof the air conditioning duct;

[0025]FIGS. 11A to 11C are views illustrating a sequence of assemblageof the air conditioning duct; and

[0026]FIGS. 12A to 12C are views illustrating other examples of thecylindrical bodies mutually coupled to one another.

BEST MODE FOR CARRYING OUT THE INVENTION

[0027] The following description is merely exemplary in nature and is inno way intended to limit the invention, its application or uses.

[0028]FIG. 1 illustrates an automotive instrument panel 10 as seen froma vehicle occupant. The automotive instrument panel 10 is composed of apanel made of plastic resin to be mounted to a front portion of avehicle compartment which is not shown and includes, in a frontal view(as viewed from a front portion of the drawing), a glove-box recessedportion 11 formed at a left and lower side, a glove- compartment mountopening 12 formed below the glove box recessed portion 11, an instrumentmount opening 13 formed at a central area in a widthwise direction of avehicle, an instrument mount opening 14 formed at a right and upperside, a steering shaft receiving opening 15 formed at a right and lowerside, right and left front defroster blowout openings 16L, 16R, rightand left side defroster blowout openings 17L, 17R, a central defrosterblowout opening 18, and right and left ventilating terminal blowoutopenings 19L, 19R.

[0029]FIGS. 2 and 3 shows an air conditioning duct 20 as viewed from thevehicle passenger. The air conditioning duct 20 serves to introduce coolair or hot air into the vehicle compartment from an air conditioningunit which is now shown. The duct 20 includes an elongated cylindricaldefroster member 30 which extends horizontally in the widthwisedirection of the vehicle, a central cylindrical ventilating member 40located at a central area in the widthwise direction of the cylindricaldefroster member 30, a left side cylindrical ventilating member 50located below the cylindrical defroster member 30 at a left side of thecylindrical ventilating member 40, and a right cylindrical ventilatingmember 60 located below the cylindrical ventilating member 30 at a rightside of the central cylindrical ventilating member 40.

[0030] The central ventilating member 40, the left cylindricalventilating member 50 and the right cylindrical ventilating member 60are located along the cylindrical defroster member 30. In the presentinvention, the cylindrical defroster member 30 is referred to as “afirst cylindrical body”, and the central ventilating member 40 and theright and left cylindrical ventilating members, which are connected othe cylindrical ventilating member 30, are referred to as a “secondcylindrical body”.

[0031] Air ports 32L, 32R, 41, 51, 61 of the respective cylindricalmembers 30 to 60 are collectively located in a central area to beadjacent one other. These air ports 32L, 32R, 41, 51, 61 are coupled toair outlets of the air conditioning unit which is now shown. The airports 32L, 32R, 41, 51, 61 serve as respective openings facing in afront direction of a vehicle body.

[0032] As shown in FIG. 3, the cylindrical defroster member 30 has asubstantially bilateral symmetric configuration in structure. Thecylindrical member 30 is constructed of a unitarily formed product,shaped by a blow forming, which has a partition wall 31 located at acenter in the widthwise direction for bisecting the cylindrical member30 into left and right side components, air inlets 32L, 32R located atleft and right sides of the partition wall 31, a left horizontal section33L communicating with the left air inlet 32L and extending leftward, aleft suspended section 34L extending downward from a left distal end ofthe horizontal section 33L, a left defroster branch segment 35L branchedoff leftward from a left side of the left suspended section 34L, a righthorizontal section 33R communicating with the right air inlet 32R andextending rightward, a right suspended section 34R extending downwardfrom a right distal end of the horizontal section 33R, and a rightdefroster branch segment 35R branched off rightward from a right side ofthe right suspended section 34R.

[0033] Further, the cylindrical defroster member 30 has blowout openings36L, 36R which open in substantially entire parts of front surfaces (ata planar side of FIG. 3 and will be hereinafter referred to in the samemanner) of the left and right horizontal sections 33L, 33R, left andright blowout openings 37L, 37R opening toward the front of the vehiclecompartment at lower distal ends of the left and right suspendedsections 34L, 34R, respectively, and left and right blowout openings38L, 38R opening toward the front of the vehicle compartment at lowerends of the left and right defroster branch segments 35L, 35R,respectively.

[0034] The central cylindrical ventilating member 40 is constructed of aunitarily formed product, shaped by a blow forming, which has an airinlet 41, a cylindrical body 42 communicating with the air inlet 41, anda blowout opening 43 opening toward the front of the vehicle compartmentat a lower distal end of the cylindrical body 42.

[0035] The left cylindrical ventilating member 50 is constructed of aunitarily formed product, shaped by a blow forming, which has an airinlet 51, a left horizontal section 52 communicating with the air inlet51 and extending leftward, a left suspended section 53 extendingdownward from a left distal end of the left horizontal section 52, and ablowout opening 54 opening toward the front of the vehicle compartmentat a lower distal end of the left suspended section 53.

[0036] The right cylindrical ventilating member 60 is constructed of aunitarily formed product, shaped by a blow forming, which has an airinlet 61, a right horizontal section 62 communicating with the air inlet61 and extending rightward, a right suspended section 63 extendingdownward from a right distal end of the right horizontal section 62, anda blowout opening 64 opening toward the front of the vehicle compartmentat a lower distal end of the right suspended section 63.

[0037] The respective blowout openings of the air conditioning duct 20and the respective blowout openings of the instrument panel 10 shown inFIG. 1 are correlated in a manner as described below.

[0038] (1) The blowout openings 36L, 36R, which are formed in the leftand right horizontal sections 33L, 33R of the cylindrical defrostermember 30, are connected to the front defroster blowout openings 16L,16R shown in FIG. 1.

[0039] (2) The blowout openings 38L, 38R, which are formed in the leftand right suspended sections 34L, 34R of the cylindrical defrostermember 30, are connected to the terminal defroster blowout openings 19L,19R.

[0040] (3) The blowout openings 38L, 38R, which are formed in the leftand right defroster branch sections 35L, 35R of the cylindricaldefroster member 30, are connected to the side defroster blowoutopenings 17L, 17R.

[0041] (4) The blowout opening 43, which is formed in the centralcylindrical defroster member 40, is connected to the central ventilatingblowout opening 18.

[0042] (5) The blowout openings 54, 64 of the left and right cylindricalventilating members 50, 60 are connected to the terminal ventilatingblowout openings 19L, 19R.

[0043] The cylindrical defroster member 30 has a plurality of fixturesegments 30 a to 30 g which are formed in the left and right horizontalsections 33L, 33R and the left and right suspended sections 34L, 34R.These fixture segments 30 a to 30 g are formed along an elongateddirection of the cylindrical defroster member 30.

[0044] The central cylindrical ventilating member 40 has a plurality offixture segments 40 a, 40 b. These fixture segments 40 a, 40 b arecoupled to the aforementioned fixture segments 30 c, 30 d of thecylindrical defroster member 30.

[0045] The left cylindrical ventilating member 50 has a plurality offixture segments 50 a, 50 b. These fixture segments 50 a, 50 b arecoupled to the aforementioned fixture segments 30 a, 30 b of thecylindrical defroster member 30.

[0046] The right cylindrical ventilating member 60 has a plurality offixture segments 60 a, 60 b, 60 c. These fixture segments 60 a, 60 b, 60c are coupled to the aforementioned fixture segments 30 e, 30 f, 30 g ofthe cylindrical defroster member 30.

[0047] The air conditioning duct 20 has a plurality of leg portions 39A,39B, 39C formed on upper parts of the cylindrical defroster member 30.Left and right sides of the central cylindrical ventilating member 40are formed with leg portions 45, 45, respectively. The left horizontalsection 52 of the left cylindrical ventilating member 50 is formed witha leg portion 55. The right horizontal section 62 of the rightcylindrical ventilating member 60 is formed with a leg portion 65. Theseleg portions 39A, 39B, 39C, 45, 45, 55, 65 are mounted to the instrumentpanel 10 shown in FIG. 1.

[0048] By coupling the fixture segments 30 a to 30 g of the cylindricaldefroster member 30 and the fixture segments 40 a, 40 b, 50 a, 50 b, 60a to 60 c of the other cylindrical members 40 to 60 to a fixture member71 which is described below, the individually formed cylindrical members30 to 60 are mutually united to one another to assemble the airconditioning duct 20 in a unitary structure.

[0049] Thus, by coupling the plural cylindrical members 30 to 60together, the air conditioning duct 20 is maintained in an entirestructure, ensuring an entire rigidity of the air conditioning duct 20.

[0050] Also, the presence of the plurality of the fixture segments 30 ato 30 g formed along the longitudinal direction of the cylindricaldefroster member 30 to be coupled to the fixture member 71 which isdescribed below enhances the entire shape of the air conditioning duct20 as compared to a structure wherein other cylindrical members 40 to 60are coupled to the cylindrical member 30 by means of single pieces ofthe fixture members 71, respectively, ensuring an adequate degree ofrigidity in the entire structure of the air conditioning duct 20.

[0051] The plurality of the leg portions 39A, 39B, 39C, 45, 45, 55, 65of the uniformly configured air conditioning duct 20 can be mounted tothe instrument panel 10 in an easy manner. Further, the presence of theair conditioning duct 20, with a high rigidity in structure, mounted tothe instrument panel 10 leads to an increased rigidity in the instrumentpanel 10.

[0052]FIG. 4 shows a structure wherein the cylindrical body 42 of thecentral ventilating member 40 is joined to the left horizontal section33L of the cylindrical defroster member 30.

[0053] The cylindrical defroster member 30 has a flat fixture segment 30c formed at a bottom in the vicinity of the air inlet 32L. The centralventilating member 40 has a flat fixture segment 40 a formed in aceiling in the vicinity of the air inlet 41. The fixture segments 30 cand 40 a are overlapped and coupled to one another by the fixture member71 composed of a rivet, thereby coupling the cylindrical members 30 and40 to one another. Thus, the presence of the coupling portions formed atareas in the vicinity of the air inlets (openings) 32L, 41 provides anease of handling to the coupling portions, thereby improving couplingwork for the mutual cylindrical members 30, 40.

[0054] A leg portion 39A, which extends near a rear surface 10 a of theinstrument panel 10, is formed in a unitary structure with the lefthorizontal section 33L and is fixedly secured to the rear surface 10 aof the instrument panel 10 by a vibrating deposition technology. The legportion 39A has a mount surface 39 a formed with a plurality ofprojections 39 b, 39 b. These projections 39 b, 39 b are secured to therear wall 10 a by the vibrating deposition.

[0055] The blowout opening 43 of the central ventilating cylindricalmember 40 serves as a part of an air blowout conduit which extendstoward the instrument panel 10. The outlet 43 a of the air blowoutconduit is formed in a bell-mouthed shape. In the drawing, referencenumeral 72 refers to a spacer and reference numeral 73 refers to a heatinsulation material for precluding dew condensation.

[0056]FIG. 5 shows a structure wherein the left horizontal section 52 ofthe left cylindrical ventilating member 50 is joined to the lefthorizontal section 33L of the cylindrical defroster member 30.

[0057] The cylindrical defroster member 30 has a front and lower portionformed with a tongue shaped fixture segment 30 b. The left cylindricalventilating member 50 has a front and upward portion formed with a flatfixture segment 50 b. The fixture segments 30 b and 50 b are overlappedand coupled to one another by the fixture member 71 such that thecylindrical member 30 and the cylindrical member 50 are interconnected.

[0058]FIG. 6 shows a structure wherein the blowout opening 36L of theleft horizontal section 33L of the cylindrical defroster member 30 isjoined to the blowout opening 16L for the front defroster.

[0059] A resilient material 74 is interposed between the rear surface 10a of the instrument panel 10 and a peripheral part of the blowoutopening 36L. The resilient material 74 prevents the peripheral part ofthe blowout opening from being brought into direct abutting engagementwith the rear surface 10 a due to vibrations, etc.

[0060] The cylindrical defroster member 30 has a leg portion 39Bintegrally formed with the left horizontal section 32L and extendingtoward the rear surface 10 a of the instrument panel 10. The leg portion39 b has a mount surface 39 a formed with a single piece of projection39 b for mounting the leg portion 39 b onto the rear surface 10 a of theinstrument panel 10 by the vibration deposition technique. Theprojection 39 b is partly joined to the rear surface 10 a of theinstrument panel 10 by the vibrating deposition.

[0061]FIG. 7 shows a structure wherein the left cylindrical ventilatingmember 50 is mounted onto the instrument panel 10.

[0062] The left cylindrical ventilating member 50 has a leg portion 55integrally formed with the left horizontal section 52 so as to extendtoward the rear surface 10 a of the instrument panel 10. The leg portion55 has a mount surface 55 a formed with a plurality of projections 55 b,55 b with a view to enabling the leg portion 55 to be mounted onto therear surface 10 a of the instrument panel 10 by the vibratingdeposition. These projections 55 b, 55 b are secured to the rear surface10 a of the instrument panel by the vibrating deposition. That is, whenoverlapping the mount surface 55 a of the leg portion 55 over the rearsurface 10 a of the instrument panel 10 and holding an overlapped areawith a press tool which is not shown with a view to implementing thevibrating deposition work, the plural (for example, two pieces)projections 55 b, 55 b are brought into contact with the rear surface 10a.

[0063] Other leg portions 39A, 45, 45, 65 shown in FIG. 3 have similarstructures.

[0064] Conventionally, the leg portion 55 had the mount surface 55 aformed with a single piece of projection. In contrast to a structurewherein a contact surface area is provided by the single piece ofprojection, an entire contact surface area of the plural projections 55b, 55 b in the present invention may substantially have the same valueas that of the single piece of projection. Thus, the contact surfacearea of each projection 55 b is decreased by such an amount. To thisend, for example, the projection 55 b may have a reduced widthwisedimension. The presence of the individual projections 55 b each with thereduced surface contact area enables a heat value, generated whenexecuting the vibrating deposition, to be regulated by such amount.Consequently, it is possible to further reliably preclude the instrumentpanel 10 from being formed with a sink mark or an irregular gloss. Incontrast, if each of the projections 55 b in the present invention isdesigned to have the same contact surface area as that of theconventional projection, a total contact surface area of the pluralprojections 55 b is increased to have a larger value than that of theconventional projection. With such an arrangement, a deposition surfacearea is increased, thereby enhancing a further sufficiently improveddeposition with increased strength.

[0065]FIG. 8 shows a structure wherein the left suspended section of theleft cylindrical ventilating member 50 is joined to the left suspendedsection 34L of the cylindrical defroster member 30.

[0066] The cylindrical defroster member 30 has the flat fixture segment30 a formed at a front portion of the left suspended section 34L. Theleft cylindrical ventilating member 50 has the tongue-shaped fixturesegment 50 a which extends upward from an upper corner of the leftsuspended section 53. The fixture segments 30 a and 50 a are overlappedand coupled together by means of the fixture member 71, thereby joiningthe cylindrical members 30 and 50 into one piece.

[0067] The blowout opening 37L of the cylindrical defroster member 30and the blowout opening 54 of the left cylindrical ventilating member 50serve as air blow out conduits which extends toward the instrument panel10. The outlets 37 a, 54 a of these members are formed in a bell-mouthedshape.

[0068]FIGS. 9A and 9B are views illustrating operations in the vicinityof the outlets of the air blowout conduits of the cylindrical members,respectively.

[0069]FIG. 9A shows a structure wherein an air discharge pipe 75 islocated in the blowout opening (which is exemplified with respect to anexample of the left terminal ventilating blowout opening 19L) of theinstrument panel 10. The air bleed pipe (which is exemplified withrespect to an example of the air blowout opening 54) extends from eachof the cylindrical members 30 to 60 toward the instrument panel 10. Theoutlet 54 a of the air blowout tube 54 has a bell-mouthed shape so as tomate with the aforementioned air discharge pipe 75 mounted at theinstrument panel 10.

[0070] Assume that, in a state wherein the cylindrical members 30 to 60are mounted to the instrument panel 10, the outlet 54 a of the airblowout tube 54 is slightly dislocated from the blowout opening 19L dueto mounting error of the air blowout tube 54. Since the outlet 54 a ofthe air blowout tube 54 is not fixed to the instrument panel 10, the airblowout tube 54 is deformable due to own resilient deformingcharacteristic. Inserting the air discharge pipe 75 into the air bleedpipe 54 into the air blowout opening 19L after mounting each of thecylindrical members 30 to 60 to the instrument panel 10 enables theoutlet 54 a of the air blowout tube 54 to be mated with the airdischarge pipe 75. As a result, the outlet 54 a, which is slightlydislocated, is urged by the air discharge pipe 75 to be deformed. FIG.9B shows a state wherein the air blowout tube 54 is aligned with the airdischarge pipe 75.

[0071] The outlets of the other air bleed pipes (air blowout openings)36L, 36R, 37L, 37R, 38L, 38R, 43, 64 are aligned in the same manner aspreviously noted.

[0072] Now, a sequence of method for fabricating and mounting the airconditioning duct 20 with the structure mentioned above is describedwith reference to FIGS. 10 and 11.

[0073]FIGS. 10A to 10D shows a fabricating sequence for the airconditioning duct. The air conditioning duct 20 is fabricated by a blowshaping technique.

[0074] First, in FIGS. 10A and 10B, left and right forming dies 81L, 81Rare held in an open state, and heated and melted resin is extruded in atube shape from a die head 82 of an extruder which is not shown, therebyimplementing a preliminary forming step. The tube-shaped resin isreferred to as a parison 83. Subsequently, the left and right formingdies 81L, 81R are matched to sandwich the parison 83 in the meltedstate.

[0075] Next, in FIG. 10C, compressed air is blown into an internal partof the parison 83, thereby expanding the parison 83 along formingsurfaces of the left and right forming dies 81L, 81R to form a product.

[0076] Lastly, in FIG. 10D, the left and right forming dies 81L, 81R areopened, allowing the solidified product, composed of the cylindricalmember (for example, the cylindrical member 30), to be removed.

[0077] With such a sequence described above, the cylindrical member isfabricated by the blow forming technique. For example, since thecylindrical member, which has the leg portions, is formed by blowforming in a unitary structure, even if the cylindrical member has alarge structure with a relatively complicated shape, the cylindricalmember can be formed in an easy manner with an increased air tightrelationship, resulting in a reduction in the number of component parts.As a consequence, it is possible for the cylindrical members to bereduced on manufacturing cost.

[0078] Now, a method for assembling the duct onto the instrument panel10 is described below in detail in conjunction with FIGS. 11A to 11C.

[0079] First, as shown in FIG. 11A, all the cylindrical members, whichare shaped by blow forming in the forming method shown in FIGS. 10A to10D, are prepared (in a first step). For example, the cylindricaldefroster member 30 unitarily formed with the leg portion 39A in theforming method discussed above and the central cylindrical ventilatingmember 40 are prepared. When shaping the cylindrical members 30, 40 byblow forming, undesired parts 84 to 86 are formed during the formingstep.

[0080] The aforementioned undesired parts 84 to 86 are cutout andremoved, finishing the shapes of the cylindrical members 30, 40 (in asecond step). For example, removing the undesired parts 84 to 86 allowsthe air inlets 32L, 41 and the air blowout opening 43 to be formed.Thus, it is easy for the undesired parts 84 to 86 to be removed tofinish the shapes of the cylindrical members 30, 40.

[0081] Next, as shown in FIG. 11B, the central cylindrical ventilatingmember 40 is mated with the cylindrical defroster member 30 and both ofthese component parts are joined together by the plurality of fixturemembers 71 (of which only one piece is shown in this drawing) (in athird step). In such a manner, the air conditioning duct 20 is obtained.

[0082] Lastly, as shown in FIG. 11C, mounting the leg portion 39A to theinstrument panel 10 by the vibrating deposition technique (in a fourthstep) completes an assembling work for the air conditioning duct 20. Inparticular, locating the air conditioning duct in a given position withrespect to the rear surface 10 a of the instrument panel 10 aligns theblowout opening 43 in a fixed place. In addition, placing the legportion 39A onto the rear surface 10 a of the instrument panel 10 allowsan overlapped area to be pressed with a given pressing force by pressdies 88, 88. Under such a condition, either the instrument panel 10 orthe leg portion 39A is vibrated with a minute amplitude (of, forexample, about 2 mm) at a given frequency (of, for example, about 100Hz). A vibrating direction is aligned, for example, in a front and reardirection with respect to the drawing. The presence of frictional heatcaused by the vibration allows the instrument panel 10 and the legportion 39A to be deposited to one another. Thus, the leg portion 39A isdeposited to the instrument panel 10 by the vibrating deposition.

[0083] With such a manner, the method for mounting the air conditioningduct of the present invention allows the plurality of cylindricalmembers to be individually formed and then allows the respectivecylindrical members to be unitarily joined with the plural fixturemembers to for the air conditioning duct 20, thereby permitting the airconditioning duct 20 in the unitary structure to be mounted to theinstrument panel by the vibrating deposition.

[0084] For example, even in a case where the air conditioning duct 20has a complicated structure which has a plurality of ventilatingpassageways in communication with the plural openings such as the airinlets 32L, 41 located in a neighboring relationship, it is possible tomanufacture the air conditioning duct in an easy manner. Further, sincethe air conditioning duct 20 in the unitary structure can be mounted tothe instrument panel 10 by merely carrying out the vibrating deposition,a mounting workability is highly improved.

[0085]FIGS. 12A to 12C show other joined structures between thecylindrical members of the present invention.

[0086] The fixture member 71 for joining the cylindrical members 30 to60 may be composed of a rivet, for example, a staple 71A shown in FIG.12A, a screw 71B shown in FIG. 12B or a clip.

[0087] Also, the cylindrical members 30 to 60 may be directly joined bythe vibrating deposition, an ultrasonic deposition or a hot caulking ina manner as shown in FIG. 12C in place of using the fixture member 71.

[0088] As will be apparent from the foregoing description, as shown inFIGS. 2 and 3, the present invention features the provision of the airconditioning duct 20 which includes the first cylindrical body composedof the cylindrical defroster member 30, and the second cylindrical bodyplaced along the first cylindrical body and composed of the centralcylindrical ventilating member 40 and the left and right cylindricalventilating members 50, 60, the plurality of fixture members 71 (seeFIG. 4) for joining the first and second cylindrical bodies 30 to 60,and the leg portions 39A to 39C, 45, 45, 55, 65 which extend from atleast one of the first and second cylindrical bodies toward theinstrument panel 10 shown in FIG. 1.

[0089] That is, the air conditioning duct 20 with the complicatedstructure is divided into the plural pieces of the cylindrical bodies 30to 60. Joining these plural pieces of the cylindrical bodies 30 to 60 bythe plural fixture members 71 allows one set of air conditioning duct 20to be assembled into one piece. The leg portions 39A to 39C, 45, 45, 55,65 of the air conditioning duct 20 with such a structure are enabled toextend toward the instrument panel 10 to be fixedly mounted thereon.Even if the air conditioning duct 20 has the complicated structure, thepresence of the separate plural cylindrical bodies 30 to 60 which formthe air conditioning duct allows the individual cylindrical bodies 30 to60 to have simplified structures, respectively. Thus, the airconditioning duct 20 can be manufactured in an easy manner.

[0090] In addition, the presence of the first and second cylindricalbodies which are joined together in the unitary structure allows the airconditioning duct 20 to be fully maintained in an entire shape, whileenhancing an adequate entire rigidity of the air conditioning duct 20.Accordingly, it is possible for the leg portions 39A to 39C, 45, 45, 55,65 of the unitarily formed air conditioning duct 20 to be readilymounted to the instrument panel 10. Further, since the air conditioningduct 20 having the increased rigidity is mounted to the instrument panel10, the instrument panel 10 also has an increased rigidity.

[0091] In the above preferred embodiment, the first cylindrical body andthe second cylindrical body have a relative relationship with respect toone another. When the first cylindrical body is used as a reference, thesecond cylindrical body is placed along the first cylindrical body. Incontrast, when the second cylindrical body is used as a reference, thefirst cylindrical body is placed along the second cylindrical body.Thus, it is arbitrarily possible for the first cylindrical body to bereferred to as the second cylindrical body and for the secondcylindrical body to be referred to as the first cylindrical body.

[0092] Furthermore, the aforementioned cylindrical members 30, 40, 50,60 have relative relationships. Accordingly, either one of or two of therespective cylindrical members 30, 40, 50, 60 is arranged to serve asthe first cylindrical body, while remaining cylindrical members servingas the second cylindrical body. For example, it is arbitrary for thecylindrical ventilating member 50 and the right cylindrical ventilatingmember 60 to be joined to the central cylindrical member 40 with theplural fixture members 71. Using the central cylindrical ventilatingmember 40 as the first cylindrical body and arranging the remainingcylindrical members 30, 50, 60 as the second cylindrical body may allowthe second cylindrical body to be placed along the first cylindricalbody for thereby joining the first and second cylindrical bodiestogether. Also, it is arbitrary for the number of pieces to be employedas the cylindrical members which constitute the first and secondcylindrical bodies.

[0093] Further, the joining positions of the respective cylindricalmembers are selected such that the rigidity of the entire structure ofthe air conditioning duct 20 is ensured after the air conditioning duct20 is assembled with the cylindrical members 30 to 60 whereupon, afterthe air conditioning duct 20 is mounted to the instrument panel 10, anentire rigidity of the air conditioning duct 20 is enhanced.

[0094] In addition, it is arbitrary for the leg portions 39A, 39B, 39C,45, 45, 55, 65 to have any shapes, dimension or the number of pieces orfor the mounting surfaces, to which the leg portions are to be mounted,to have any shape, dimension or the number of pieces.

[0095] Further still, the outlets of the air blowout tubes (the airblowout openings) 36L, 36R, 37L, 37R, 38L, 38R, 43, 54, 64 may have thebell-mouthed shapes, respectively, so as to be mated with the airdischarge pipes 75 mounted to the instrument panel 10. The bell-mouthedshape may include a tapered shape, a funnel-shaped profile and abell-shape.

[0096] Industrial Applicability

[0097] As noted above, an air conditioning duct of the present inventionallows an air conditioning duct with a complicated configuration to beformed with a plurality of cylindrical members which are separatelyformed. Since the plural cylindrical members are joined together with aplurality of fixture members, each cylindrical member has a relativelysimplified structure, providing an ease of manufacturing the airconditioning duct with the complicated shape in a simple fashion to beuseful from the point of productivity of a vehicle and from a reducedcost.

1. An air conditioning duct to be positioned on a rear surface of avehicular instrument panel, comprising: a first cylindrical body; asecond cylindrical body placed along said first cylindrical body; aplurality of fixture members for joining said first and secondcylindrical bodies to one another; and a leg portion extending from atleast one of said first and second cylindrical bodies toward saidvehicular instrument panel.
 2. The air conditioning duct according toclaim 1, wherein said fixture members are placed along a lengthwisedirection of said first cylindrical body in a plurality of pieces. 3.The air conditioning duct according to claim 2, wherein at least one ofsaid fixture members is located in the vicinity of openings of saidfirst and second cylindrical bodies.
 4. The air conditioning ductaccording to claim 1, wherein said first and second cylindrical bodiesinclude respective air blowout tubes extending toward said vehicularinstrument panel, and wherein outlets of said air blowout tubes areformed in bell-mouthed shapes so as to mate with air discharge pipesmounted to said vehicular instrument panel.
 5. The air conditioning ductaccording to claim 1, wherein said leg portion is designed to be mountedto said vehicular instrument panel by a vibrating deposition and has amounting surface formed with a plurality of projections.
 6. A method formounting an air conditioning duct, comprising the steps of: preparing afirst cylindrical body and a second cylindrical body which are unitarilyformed with leg portions, respectively; placing said first cylindricalbody and said second cylindrical body along to one another and joiningsaid first and second cylindrical bodies with a plurality of fixturemembers; and mounting said respective leg portions to said vehicularinstrument panel by a vibrating deposition.